The General Service Medal (1918 GSM) was instituted to recognise service in minor Army and Air Force operations for which no separate medal was intended. It was equivalent to the 1915 Naval General Service Medal. Both these medals were replaced by the General Service Medal in 1962.

Seventeen clasps were approved for the 1918 GSM. These clasps consist of small metal bars into which the name of the relevant campaign or theatre of operations was moulded. The clasps were then attached to the medal's suspension bar. The 1918 GSM was never awarded without a clasp.

South Persia

Service at or near Bushire with Major-General J.A. Douglas and Brigadier-General A. M. S. Elsmie from 12 November 1918 – 22 June 1919

Service at or near Bandar Abbas with Major-General Sir. P. Sykes or Lieutenant Colonel E.F. Orton from 12 November 1918 – 3 June 1919

Kurdistan

This clasp was awarded for the following:

At Kirburk or north of a line east and west through Kirburk between 23 May and 31 July 1919.

At Dohok or north of a line east and west through Dohok between 14 July and 7 October 1919.

North of the advanced bases near Akra and Amadia between 7 November and 6 December 1919.

The 1924 Army Order No. 387 and Army Instruction (India) No. 132 of 1925 extended this clasps eligibility requirements to cover operations in Kurdistan. These additional qualify periods are

Operations under Air Marshal Sir J.M. Salmond or Colonel Commandant B. Vincent between 19 March to 18 June 1923.

This clasp was presented to those who satisfied one of the following conditions:

Served at Ramadi or north of a line east and west through Ramadi between 10 December 1919 and 13 June 1920.

Part of an establishment within Iraq between 1 July and 17 November 1920.

N.W. Persia

Awarded to members of Noperforce (North Persia Force) and those on various lines of communications serving under Brigadier-General H.F. Bateman-Champain in 1920.

Southern Desert Iraq

Awarded to the RAF for its services against the Akhwan in the Southern Desert, under the command Air Commodore T.C.R. Higgins between 8 and 22 January 1928, or under the command of Wing Commander E.R.C. Nanson between 22 January and 3 June 1928.

North Kurdistan

For operations against Sheik Admed of Barzan in the area Diana – Erbil – Aqra – Suri due north to the Turkish frontier, between the dates of 15 March and 21 June 1932.

Palestine

For service in Mandatory Palestine between the dates 19 April 1936 and 3 September 1939, during the Arab Revolt.

S.E. Asia 1945–46

Awarded to British personnel involved in South-East Asia after the Japanese surrender of 15 August 1945, for various activities such as guarding Japanese POWs and maintaining law and order. By November 1946, British troops had handed over their responsibilities to the territories former colonial powers.

Bomb and Mine Clearance 1945–49

Awarded for a total of 180 days active service in the removal of mines and bombs in the UK between May 1945 and September 1949. Queen Elizabeth II approved the eligibility to run to 1956.

Those who qualified for the original period, 1945–1949, were awarded this clasp

Bomb and Mine Clearance 1949–56

Those who qualified in the period 1949–1956 were awarded this clasp

Palestine 1945–48

Part of the resolution of the 1936-9 revolt was the imposition of an immigration quota for Jews wishing to enter Palestine. This was opposed by the Jewish settlers in Palestine and in 1944, a guerrilla war was launched against the British forces there, principally by the Irgun and Lehi. While service in this conflict prior to 1945 is counted as World War Two service, service between 27 September 1945 (the date a "state of emergency" was declared) and 30 June 1948 (when the last British troops departed) is acknowledged by this clasp to the GSM.

Berlin Airlift

As a result of the 2012 Independent Medal Review conducted by Sir John Holmes, from 1 March 2015 a Berlin Airlift clasp will be awarded to RAF or civilian aircrew with at least one day's service in the Berlin Airlift operation from 25 June 1948 to 6 October 1949 inclusive.[2]

Malaya

For service in Malaya and Singapore against communist guerrilla forces.

The qualifying dates for service were between 16 June 1948 and 31 July 1960. For the Colony of Singapore, the date period was between 16 June 1948 to 31 January 1959.

Canal Zone

Awarded for 30 days continuous service during the period October 1951 – October 1954 within certain specified geographical boundaries in Egypt. This GSM was awarded some 50 years later following representation to Prime Minister Tony Blair.

Cyprus 1955-59

In 1956 the Cypriot movement for union with Greece (called "Enosis") started under the leadership of Archbishop Makarios and General George Grivas. The General led the guerrilla organisation EOKA against the British troops stationed on the island. The conflict was often a bloody affair, involving 40,000 British troops over 4 years. As a result of the 2012 Independent Medal Review conducted by Sir John Holmes, from 1 October 2014 the qualifying period was reduced from 120 to 90 days service, to bring it into line with the Kenya campaign.[3]

Near East

This clasp was awarded for service in the Middle east in the period 31 October to 22 December 1956. This is the conflict often referred to as the Suez Crisis, or by its codename of Operation Musketeer.

Arabian Peninsula

Due to a disagreement about land and associated oil rights, the Iman of Oman rebelled against the Sultan of Muscat. After initial setbacks, in 1955 the Sultan called for assistance from UK forces. It was not until British special forces were deployed that the rebels were dislodged from their territory in the Jebel Akhbar mountains.

The qualifying period for this clasp is 30 days' service between 1 January 1957 and 30 June 1960, in the Aden Colony or protectorate and the Sultanates of Muscat and Oman, or any of the adjacent Gulf states.

Brunei

For a minimum 1 days' service in at least one of the operational areas located in the State of Brunei, North Borneo or Sarawak between 8 December 1962 and 23 December 1962.